Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Consolidated Net Income			$ 926	$ 2,529	$ 2,435
Qualifying hedges:
Changes in fair value, net of tax			57	(136)	(13)
Reclassification adjustment for amounts included in net income, net of tax			(60)	69	6
Pension and other postretirement benefit plans:
Benefit plan net gain (loss), net of tax			17	13	(2)
Reclassification adjustment for amounts included in net income, net of tax			(23)	4	7
Total other comprehensive income (loss)			(9)	(50)	(2)
Less:
Dividends on preferred and preference stock of subsidiaries			38	45	54
Comprehensive income attributable to noncontrolling interests			46	36	14
Comprehensive Income			833	2,398	2,365
ALABAMA POWER CO
Consolidated Net Income			866	839	811
Qualifying hedges:
Changes in fair value, net of tax			1	(2)	(5)
Reclassification adjustment for amounts included in net income, net of tax			3	4	2
Pension and other postretirement benefit plans:
Total other comprehensive income (loss)			4	2	(3)
Less:
Dividends on preferred and preference stock of subsidiaries			18	17	26
Comprehensive Income			870	841	808
GEORGIA POWER CO
Consolidated Net Income			1,428	1,347	1,277
Qualifying hedges:
Changes in fair value, net of tax			0	0	(9)
Reclassification adjustment for amounts included in net income, net of tax			3	2	2
Pension and other postretirement benefit plans:
Total other comprehensive income (loss)			3	2	(7)
Less:
Dividends on preferred and preference stock of subsidiaries			14	17	17
Comprehensive Income			1,431	1,349	1,270
GULF POWER CO
Consolidated Net Income			139	140	157
Qualifying hedges:
Changes in fair value, net of tax			(1)	1	1
Pension and other postretirement benefit plans:
Total other comprehensive income (loss)			(1)	1	1
Less:
Dividends on preferred and preference stock of subsidiaries			4	9	9
Comprehensive Income			138	141	158
MISSISSIPPI POWER CO
Consolidated Net Income			(2,588)	(48)	(6)
Qualifying hedges:
Changes in fair value, net of tax			(1)	1	0
Reclassification adjustment for amounts included in net income, net of tax			1	1	1
Pension and other postretirement benefit plans:
Total other comprehensive income (loss)			0	2	1
Less:
Dividends on preferred and preference stock of subsidiaries			2	2	2
Comprehensive Income			(2,588)	(46)	(5)
SOUTHERN POWER CO
Consolidated Net Income			1,117	374	229
Qualifying hedges:
Changes in fair value, net of tax			63	(27)	0
Reclassification adjustment for amounts included in net income, net of tax			(73)	58	1
Pension and other postretirement benefit plans:
Total other comprehensive income (loss)			(10)	31	1
Less:
Comprehensive income attributable to noncontrolling interests			46	36	14
Comprehensive Income			1,061	$ 369	216
SOUTHERN Co GAS
Consolidated Net Income	$ 114		243
Qualifying hedges:
Changes in fair value, net of tax	(1)		(5)
Reclassification adjustment for amounts included in net income, net of tax	0		1
Pension and other postretirement benefit plans:
Benefit plan net gain (loss), net of tax	27		(1)
Reclassification adjustment for amounts included in net income, net of tax	0		0
Total other comprehensive income (loss)	26		(5)
Less:
Comprehensive income attributable to noncontrolling interests	0		0
Comprehensive Income	$ 140		$ 238
Predecessor | SOUTHERN Co GAS
Consolidated Net Income		$ 145			373
Qualifying hedges:
Changes in fair value, net of tax		(41)			0
Reclassification adjustment for amounts included in net income, net of tax		1			8
Pension and other postretirement benefit plans:
Benefit plan net gain (loss), net of tax		0			0
Reclassification adjustment for amounts included in net income, net of tax		5			12
Total other comprehensive income (loss)		(35)			20
Less:
Comprehensive income attributable to noncontrolling interests		14			20
Comprehensive Income		$ 96			$ 373